Ruminal Degradation and in vitro Crude Protein Digestibility of Gamma Irradiated Meat and Bone Meal

This study was carried out to determine effects of gamma irradiation (gamma-irradiation) at doses of 15, 30 and 45 kGy on ruminal degradability, in vitro Crude Protein (CP) digestibility and chemical composition of Meat and Bone Meal (MBM). Nylon bags of untreated or treated MBM were suspended in the rumen of three bulls for up to 48 h and resulting data were fitted to non-linear degradation model to calculate Effective Degradability (ED). Chemical composition of MBM was not affected by gamma-irradiation gamma-irradiation decreased (p < 0.05) the washout fraction and increased (p < 0.05) the potentially degradable fraction of DM. ED of DM decreased (p < 0.05) with increases in irradiation dose. gamma-irradiation decreased (p < 0.05) the washout fraction of CP from 252-191 g kg(-1) . gamma-irradiation reduced (p < 0.05) the degradation rate of the b fraction of CP. gamma-irradiation at doses of 15, 30 and 45 kGy decreased ED of CP at rumen outflow rate of 0.05 h(-1) by 4, 9 and 16%, respectively. gamma-irradiation increased (p < 0.05) in vitro CP digestibility of MBM. gamma-irradiation at doses of 30 and 45 kGy, increased in vitro CP digestibility of undegraded CF remaining in bags incubated for 16 h in the rumen by 13 and 15%, respectively. gamma-irradiation seems to be effective in increasing in vitro CP digestibility of MBM at doses > 15 kGy.